Means for use in timing the ignition in internal-combustion engines



Dec. 27, 1949 w vm ETAL 2,492,247

MEANS FOR USE IN TIMING THE IGNITION IN INTERNAL-COMBUSTION ENGINES Filed Feb. 20, 1948 Patented Dec. 27, 1949 UNITED mm; PATENT orrlcr.

MEANS FOR USE IN TIMING THE IGNITION IN INTERNAL-COLIBUSTION ENGINES John H. Weaving, Moseley, Birmingham, and Frank W. Highfleld, Woilaston, Malvern Wells, England, assignors to The Austin Motor Company Limited, Birmingham, England 7 Application February 20, 1948, Serial No. 9.886 In Great Britain February 21, 1947 2 Claims. (Cl. 175-183) The invention relates to means for checking the ignition timing of internal combustion engines, whether running under their own power or being rotated by outside power.

The invention consists in means whereby, each time the contact breaker points of the ignition system open in respect of any plug, or in respect of a selected plug, the voltage generated by an associated transformer is utilised to trip, or control, a flash of an electronic flash tube which, when such flash occurs, illuminates a mark on a rotating part of the engine conveniently the flywheel, said mark being registered against a fixed point or against a scale preferably marked in degrees of a circle the assembly thus being a stroboscopic device.

Embodiments of the invention are shown in the accompanying diagrams of which:

Figure 1 is a schematic diagram showing the application of the invention to ascertaining the precise angular position of the crank shaft of an engine where the electronic flash tube flashes when any of the plugs fire in an engine driven by its own power.

Figure 2 is a schematic diagram somewhat similar to Figure 1 but showing an application of the invention to the firing of one chosen plug.

Figure 3 is a schematic diagram showing the application of the invention to an engine which is being motored, that is to say driven by an outside source of power.

Figure 4 is an end view of an internal combustion engine with the fly-wheel exposed.

Referring first to Figures 1 and 4, A indicates the ordinary contact breaker points a, a, in a conventional distributor, and C the step-up transformer thereof, known as the coil. c is the primary winding thereof. One end of the secondary winding 0' leads to the distributor and plugs (not shown) in the usual way, the other end of the secondary being earthed. B is a low tension battery, which may be an ordinary car battery.

d indicates the primary of a, step-up transformer D having a secondary winding d, one end of which is earthed and the other end connected to the trigger electrode of an electronic flash tube F. Terminals j, j of the tube F are connected to a source of high tension D. C. supply indicated at 0,1).

The primary winding d of the transformer D is shunted across the primary winding 0 of the transformer C. G is a condenser of a capacity of about .1 mfd. H is the usual condenser shunted across the points a, a.

When the points a, a, are closed, current flows from the battery 13 through the primary windings c and d in parallel and,'at the instant the points open, a mometary high-tension current is induced in the secondary c and one of the plugs fires in the usual way. A momentary high tension current isalso induced in the secondary d imposing a momentary high-tension voltage on the trigger electrode 1 of the tube F causing the latter to give a momentary flash, the tube receiving current from the leads 0, 1:, but chiefly from discharge of the condenser G.

The flash from the tube F gives momentary illumination to a white mark P (see Figure 4) depicted on the fly-wheel Q of the engine N, so that,

by persistence of vision, the mark will appear stationary and its relation to a fixed scale S can be read off, and the exact angle of the crank shaft noted at the moment of firing of any of the plugs.

In certain circumstances it is required to ascertain the exact timing of any one of the plugs. Referring to Figure 2, the primary 7' of a loosecoupled transformer J is placed in series in the lead K between the distributor and the plug of which the timing is required to be ascertained. The primary 7 has low inductance so as to cause only a slight drop in the voltage on the plug.

The secondary winding 7" connects at its one end to a terminal 22 of a source of high-tension D. C. supply and at its other end to the grid m of an electronic triode M. The cathode m of the triode M connects to the terminal 12 and the anode m is connected, through the primary winding (1, to the terminal 0 of the high-tension supply. T is a condenser of about .1 mfd. placed across the terminals '0 0 B is a grid bias battery. It is placed in series with a high resistance R to protect the winding 7''.

When the plug fires the current impulse thereto passes through the primary winding 7 and induces a voltage in the secondardy a" which gives a momentary rise in voltage on the grid m. A pulse of increased current then flows through the triode M and winding d. This causes the tube F to flash as described. with reference to Figure 2.

In other cases it is required to check the ignition timing of an engine which is being motored and in which the plugs are not fitted, or at any rate in which the plugs are not electrically connected up. A schematic diagram for this purpose is shown in Figure 3. The point a of the contact breaker is connected to one end of the winding (1 as in Figure 1, the other end of the winding d being connected to earth through the battery B. The secondary winding d is earthed 3 at one end and has its other end connected to the trigger electrode 1 as described with reference to Figures 2 and 3, as shown by full lines. The tube F will then flash each time the points open.

If it is required to check the angle of crankshaft rotation at which any one chosen plug would have fired, the winding d is connected to the trigger electrode I through a distributor S as shown by broken lines in Figure 3.

Having fully described our invention, what we claim and desire to secure by Letters Patent is:

1. Means for checking the ignition timing of an internal combustion engine, said means com prising a first additional transformer, a primary winding of said transformer placed in series in the lead to a chosen plug, a secondary winding of said transformer, an electronic triode, a grid of said triode connected to said secondary winding, a cathode of said triode connected to the negative of a source of D. C. supply, an anode of said triode, a second additional transformer, a primary of said second additional transformer, one end of said primary being connected to the positive of said source of D. C. supply and the other end connetted to said anode, a' secondary of said second additional transformer, an electronic flash tube. a separate source of current supply to said flash tube and a trigger electrode of said flash tube, one end of said secondary winding of said second additional transformer being connected to said trigger electrode, whereby the said electronic flash tube will flash when the said plug fires, and illuminate a mark on a rotating part of the engine. 2. An ignition circuit timer comprising a first circuit having a source of electrical energy, a primary of a transformer and means of impressing electrical impulses from the ignition system being tested across the primary in accordance with the timing of the ignition circuit, and a secand circuit comprising an electronic flash tube having its terminals connected to an independent source of electrical energy insuflicient to produce a flash within said tube, the tube having a trigger electrode in series with a secondary of said transformer whereby the timing of the ignition circuit is impressed on the electronic tube.

JOHN H. WEAVING. FRANK W. HIGHFIELD.

- REFERENCES crren The following references are of record in the flle of this patent:

UNITED STATES PATENTS Great Britain Oct. 27, 1932 

